1. Field of the Invention
The present invention relates to a fin-tube fin of a heat exchanger, especially to a fin-tube fin having a vortex generator.
2. Description of the Prior Art
Traditional air conditioner generally contains a compressor, a condenser, an expansion valve, and an evaporator. Normally, a fin-tube heat exchanger is used as the heat exchanger of an air conditioner as shown in FIG. 1. A traditional fin-tube heat exchanger 1 comprises a plurality of fins 11 spaced apart from adjacent ones a proper distance for passing an air flow 13 through gaps between the fins 11. A plurality of heat transfer tubes 12 extend through the fins 11 and each heat transfer tube 12 contains coolant flowing therein for heat dissipation. The main function of the heat exchanger is to facilitate heat exchange between the coolant in the heat transfer tubes 12 and the air around the heat transfer tubes 12. The main function of the fins 11 is to increase the contacting area between the coolant and the air around.
It has been a long term effort in the air conditioner industry to promote the function of the heat exchanger in consideration of power conservation. Some of the published patents have disclosed technique about promoting the heat exchange efficiency of the fins but most of the designs focus on the improvement of the traditional louver type or slit type of fins. For example, in U.S. Pat. No. 4,817,709, issued on Apr. 4, 1989, a fin structure having a slant plate formed by stamping is disclosed. Specifically, the fin has a wavy shape in which several triangular slant plates are formed by stamping and enable the air flow to generate counter-rotating vortexes at two sides of the triangular slant plate. The triangular slant plate is specifically suitable for the wavy-shaped fin not for general shape. Moreover, the heat transfer efficiency caused by the counter-rotating vortexes at two sides of the triangular slant plate is doubtful.
In U.S. Pat. No. 5,207,270, issued on May 4, 1993, a fin-tube heat exchanger is disclosed which has curved angular protuberances and straight protuberances around heat transfer tubes of each fin of the fin-tube heat exchanger. The curved angular protuberances cooperate with the straight protuberances for improving the heat transfer efficiency of the heat exchanger. In U.S. Pat. No. 5,203,403, issued on Apr. 20, 1993, a fin-tube heat exchanger is disclosed which has elliptic protuberances formed around heat transfer tubes of each fin of the fin-tube heat exchanger for promoting the heat transfer efficiency. However, the manufacturing of the heat exchanger is very complicated and high cost therefore need to be improved.
The primary purpose of the present invention is to provide a new structure of a fin geometry of a heat exchanger which is simple and easily manufactured yet effective in heat transfer. The fin geometry has a vortex generator having a plurality of ribs formed around heat transfer tubes of the fin by which the air flow passing through the heat exchanger can form a vortex effect around the heat transfer tubes for strengthening the mixture of air around thus considerably improving the heat dissipation efficiency of the fin.
Another purpose of the present invention is to provide a new structure of a fin of a heat exchanger which utilizes a pattern of ribs of a vortex generator of the fin to create a vortex effect for increasing the mixture of air and promoting the heat transfer efficiency of a stagnation area behind the heat transfer tube while not increasing the pressure drop significantly. With this new structure, the function of the heat exchanger is promoted and the total operational efficiency of the air conditioner is thus increased.
According to one aspect of the present invention, there is provided a heat exchanger comprising a plurality of fins spaced from each other in parallel and adjacent ones of the fins allowing an air flow to pass through a gap therebetween. A plurality of heat transfer tubes extends through the fins. A vortex generator comprises a plurality of protuberance ribs formed on the fin and centralized with the heat transfer tube. An air flow inlet is defined between adjacent two of the protuberance ribs and an air flow outlet is defined between other adjacent two of the protuberance ribs.
In operation, the air flow is guided from the air flow inlet, through channels defined between the vortex generator and the heat transfer tube, and passes out of the air flow outlet, thereby speeding the air flow and promoting the heat transfer efficiency of a stagnation area behind the tube, and generating vortexes at the protuberance ribs and the air flow outlet for draining outer air into the surface for better air mixing.